NSRange到Range<String.Index>
NSRange到Range<String.Index>
提问于 2014-08-05 12:01:21
如何在Swift中将NSRange转换为Range<String.Index>？
我想使用以下UITextFieldDelegate方法：
func textField(textField: UITextField!,
shouldChangeCharactersInRange range: NSRange,
replacementString string: String!) -> Bool {
textField.text.stringByReplacingCharactersInRange(???, withString: string)
回答 16
Stack Overflow用户
回答已采纳
发布于 2014-10-22 21:46:14
String的NSString版本(相对于Swift字符串)接受NSRange，因此一个简单的解决方案是将转换为 NSString first。在Swift 3和2中，委托和替换方法名称略有不同，因此取决于您使用的Swift：
Swift 3.0
func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
let nsString = textField.text as NSString?
let newString = nsString?.replacingCharacters(in: range, with: string)
}Swift 2.x
func textField(textField: UITextField,
shouldChangeCharactersInRange range: NSRange,
replacementString string: String) -> Bool {
let nsString = textField.text as NSString?
let newString = nsString?.stringByReplacingCharactersInRange(range, withString: string)
}Stack Overflow用户
发布于 2015-05-22 19:29:09
在Swift 4 (Xcode 9)中，Swift标准库提供了在Swift字符串范围(Range<String.Index>)和NSString范围(NSRange)之间进行转换的方法。示例：
let str = "abc"
let r1 = str.range(of: "")!
// String range to NSRange:
let n1 = NSRange(r1, in: str)
print((str as NSString).substring(with: n1)) //
// NSRange back to String range:
let r2 = Range(n1, in: str)!
print(str[r2]) // 因此，文本字段委托方法中的文本替换现在可以作为
func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
if let oldString = textField.text {
let newString = oldString.replacingCharacters(in: Range(range, in: oldString)!,
with: string)
// ...
}
// ...
}( Swift 3及更早版本的旧答案：)
在SWIFT1.2中，String.Index有一个初始化器
init?(_ utf16Index: UTF16Index, within characters: String)可用于正确地将NSRange转换为Range<String.Index> (包括所有表情符号、区域指示符或其他扩展的图形素集群)，而无需中间转换为NSString。
extension String {
func rangeFromNSRange(nsRange : NSRange) -> Range<String.Index>? {
let from16 = advance(utf16.startIndex, nsRange.location, utf16.endIndex)
let to16 = advance(from16, nsRange.length, utf16.endIndex)
if let from = String.Index(from16, within: self),
let to = String.Index(to16, within: self) {
return from ..< to
}
return nil
}
}此方法返回一个可选字符串范围，因为并非所有的NSRange都对给定的Swift字符串有效。
然后，可以将UITextFieldDelegate委托方法编写为
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
if let swRange = textField.text.rangeFromNSRange(range) {
let newString = textField.text.stringByReplacingCharactersInRange(swRange, withString: string)
// ...
}
return true
}逆变换是
extension String {
func NSRangeFromRange(range : Range<String.Index>) -> NSRange {
let utf16view = self.utf16
let from = String.UTF16View.Index(range.startIndex, within: utf16view)
let to = String.UTF16View.Index(range.endIndex, within: utf16view)
return NSMakeRange(from - utf16view.startIndex, to - from)
}
}一个简单的测试：
let str = "abc"
let r1 = str.rangeOfString("")!
// String range to NSRange:
let n1 = str.NSRangeFromRange(r1)
println((str as NSString).substringWithRange(n1)) //
// NSRange back to String range:
let r2 = str.rangeFromNSRange(n1)!
println(str.substringWithRange(r2)) // Swift 2的更新：
Swift 2版本的rangeFromNSRange()已经由Serhii在this answer中提供，为了完整起见，我在这里包括它：
extension String {
func rangeFromNSRange(nsRange : NSRange) -> Range<String.Index>? {
let from16 = utf16.startIndex.advancedBy(nsRange.location, limit: utf16.endIndex)
let to16 = from16.advancedBy(nsRange.length, limit: utf16.endIndex)
if let from = String.Index(from16, within: self),
let to = String.Index(to16, within: self) {
return from ..< to
}
return nil
}
}Swift 2版本的NSRangeFromRange()是
extension String {
func NSRangeFromRange(range : Range<String.Index>) -> NSRange {
let utf16view = self.utf16
let from = String.UTF16View.Index(range.startIndex, within: utf16view)
let to = String.UTF16View.Index(range.endIndex, within: utf16view)
return NSMakeRange(utf16view.startIndex.distanceTo(from), from.distanceTo(to))
}
}Swift 3的更新(Xcode 8):
extension String {
func nsRange(from range: Range<String.Index>) -> NSRange {
let from = range.lowerBound.samePosition(in: utf16)
let to = range.upperBound.samePosition(in: utf16)
return NSRange(location: utf16.distance(from: utf16.startIndex, to: from),
length: utf16.distance(from: from, to: to))
}
}
extension String {
func range(from nsRange: NSRange) -> Range<String.Index>? {
guard
let from16 = utf16.index(utf16.startIndex, offsetBy: nsRange.location, limitedBy: utf16.endIndex),
let to16 = utf16.index(utf16.startIndex, offsetBy: nsRange.location + nsRange.length, limitedBy: utf16.endIndex),
let from = from16.samePosition(in: self),
let to = to16.samePosition(in: self)
else { return nil }
return from ..< to
}
}示例：
let str = "abc"
let r1 = str.range(of: "")!
// String range to NSRange:
let n1 = str.nsRange(from: r1)
print((str as NSString).substring(with: n1)) //
// NSRange back to String range:
let r2 = str.range(from: n1)!
print(str.substring(with: r2)) // Stack Overflow用户
发布于 2015-09-03 15:18:20
Martin的This answer似乎是正确的，因为它解释了Unicode。
然而，在发布文章(Swift 1)时，他的代码没有在SWIFT2.0 (Xcode 7)中编译，因为它们删除了advance()函数。最新版本如下：
Swift 2
extension String {
func rangeFromNSRange(nsRange : NSRange) -> Range<String.Index>? {
let from16 = utf16.startIndex.advancedBy(nsRange.location, limit: utf16.endIndex)
let to16 = from16.advancedBy(nsRange.length, limit: utf16.endIndex)
if let from = String.Index(from16, within: self),
let to = String.Index(to16, within: self) {
return from ..< to
}
return nil
}
}Swift 3
extension String {
func rangeFromNSRange(nsRange : NSRange) -> Range<String.Index>? {
if let from16 = utf16.index(utf16.startIndex, offsetBy: nsRange.location, limitedBy: utf16.endIndex),
let to16 = utf16.index(from16, offsetBy: nsRange.length, limitedBy: utf16.endIndex),
let from = String.Index(from16, within: self),
let to = String.Index(to16, within: self) {
return from ..< to
}
return nil
}
}Swift 4
extension String {
func rangeFromNSRange(nsRange : NSRange) -> Range<String.Index>? {
return Range(nsRange, in: self)
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/25138339
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